The invention relates to a device for the suppression of multiple registrations of identical data in a data store, resulting from shuttle movements between the inquiry and response mechanisms of a data system, in which such mechanisms are movable relative to one another. The invention is particularly applicable to a system for the automatic number reporting of freight cars, and for point-to-point train control in the railroading field.
In data transmission systems involving inquiry and response mechanisms which are movable relative to one another, as a result of shuttle movements between the inquiry and response mechanisms, occasionally the same data is multiply transmitted. Thus, in the railroading field, for example, in a system for automatic reporting of freight car numbers, the car number of a freight car can be multiply transmitted to an interrogation or reading device if the car involved shuttles back and forth in the vicinity of the inquiry device, and thus repeatedly passes the inquiry point or the reading range of the inquiry device. Shuttle movements of this type can, for example, be caused in switching operations by the nonuniform movement of the cars, carrying the response devices, over the switching hump. The freight car number derived in the response device is then multiply transmitted to the inquiry device and multiply stored in an associated data store. As a result of such multiple registrations of the same freight car numbers, the numbers stored in such data store no longer correspond to the actual operational conditions.
If the data stored in the data memory is to be effectively utilized for further control and regulation in the operation, multiple registrations of identical data must be suppressed. In systems in which a particular directional movement is involved of the inquiry or response devices, or is specifically established, the desired results may be achieved, for example, by the use of devices which constantly determine the actual movement direction of the vehicles and which, in the case of an actual movement direction deviating from the prescribed movement direction, effects an erasure of the most recently read-in data. However, such devices are relatively costly and further, substantially increase the susceptibility to system disruption and failure. In addition, this type of operation has the disadvantage that, when there is a reverse movement of a car device within the range of the inquiry device, a car number could be lost, as a result of which the stored content of the data store again does not correspond to the actual operational conditions.